Lubricant



' evidence to prove that it is superior to the condesirable properties of being entirely odorless,

Patented Mar. 4, 194 1 I I UNITED STATES PATENT OFFICE LUBRJCAN T Waldo L. Steiner, Ponca City, Okla., assignor, by

mesne assignments, to The Lubrl-Zol Development Corporation, Cleveland, Ohio, a corporation of Delaware No Drawing. Application January 22, 1940,

Serial No. 315,126 I 4 Claims. (Cl. 252-31) My invention relates to a cutting lubricant in less, they are invariably dark in color and are particular, and lubricants generally, and more usually rather viscous around 30 F. particularly to a lubricant designed for lubrica- There are many solvents for sulphur, one of v tion of cutting tools and machines for cutting the best being carbon bisulphide This solvent 5 and threading metallic pipes, rods, boltsand the could not be used commercially in a cutting lubri- 5 like. cantbecause of its high volatility and inflam- This application is a continuation in part of mability. There are other solvents for sulphur my co-pending application Ser. No. 62,170, filed to which these objections could not apply which, Feb. 3, 1936, now Patent No. 2,188,255 of Jan. 23, for other reasons, such as obnoxious odor and in- 1940. solubility in petroleum oil,Ido not prefer. Phenol 10 Heretofore, cutting lubricants consisted mainly and aniline are examples. The greatest difliculty of blends of lubricating oil and a chemical comin finding a suitable solvent for sulphur for a bination of sulphur, usually, with afatty comcutting oil is to discover one which will not allow pound. These early types of cutting oils are sulphur to separate out when the mixture is fairly satisfactory for most uses but nevertheless stored at relatively low temperatures. Naturally, 15 have certain distinct disadvantages. Most of a marketable cutting lubricant must be stable them have an objectionable odor andare very under all kinds of possible storage conditions dark in color and some are very ineflicient. Usu- Such as might be encountered in winter.

ally they are rather expensive and diflicult to I have found that solutions of Su p in prepare. A great number have an irritating eftain derivatives of naphthalene and similar high 20 feet on the skin of the operator. Some are exboiling aromatic compounds when added to a tremely viscous when cold and are therefore very petroleum lubricant, do not precipitate out sulunsatisfactory on cold mornings in many shops phur even at y low temperatures When the which are not well heated. Some of the newer amount of sulphur iS p Within Certain limits, cutting lubricants contain sulphur compounds and these form the preferred solutions for use in 20 other than those derived from fatty acid derivamy invention. Naphthalene itself is odoriferous tives. In all of the above compounds, however, and not very soluble in petroleum oils at low tomthe sulphur is in chemical combination. Furperatures and. therefore, is not p r e It thermore, other things being equal, the efliciency however, a very efllcient solvent for sulphur, es-

of this type of cutting oil is largely dependent pecial y at i h te p ture C i e i on the instability ofthe sulphur compound. The stigation was therefore give 1 the p more stable the compound the less eflicien't it is thalene derivatives which are soluble in petroas an aid in cutting" and relatively more of it leum at ow t p s h Work led to the will have to be used for a satisfactory cutting discovery that, among the better sulphur solvents lubricant. On the other hand, if the compound w ich are soluble in petroleum at low temp 35 is very unstable, the cutting oil made from it will I res re he chl rine bearin nd other halogen likely deteriorate in storage. bearing derivatives of naphthalene. Further- The object of my inventi i t provide an more, the best suited of the chlorine bearing deimproved cutt ing lubricant. I have discovered riVatiVeS are e p and P 40, that an imprqved and superior cutting lubricant thalenes. These two compounds were found to 40 'may be prepared by blending a petroleum lubribe able to dissolve more sulphur for a given cant with a true physical solution of sulphur. in weight when mixed with a petroleum lubricant certain suitable solvents. My investigation of than any other solvent investigated, either at this new type of cutting lubricant gives sufficient high or low temperatures. They have the added ventional chemically combined sulphur cutting practically colorless, and quite non-toxic. These lubricant in several ways. -In the first place, two compounds, holding sulphur in solution and much less sulphur is required to obtain the same dissolved in a petroleum lubricant, will not preefliciency for the lubricant. Secondly, it makes cipitate out sulphur when stored for several it possible to prepare a cutting lubricant very weeks at 0 F. if the sulphur content does not 50 light in color and quite odorless and one which exceed 12 per cent by weight of the chloronaphdoes not irritate the skin in the slightest degree. thalene 'in the mixture. These chloronaphtha- Also, they do not congeal at low temperatures. lenes arr themselves soluble ina petroleum lubri- While some old type lubricants'containing chemicant to the extent of about 10 per cent at 0 F.

cally combined sulphur may be obtained odor They are more soluble in the heavier lubrica ts 55 to make a cutting lubricant stable to the most adverse storage conditions from these two chloronaphthalenes, containing 1.2 per cent of physically dissolved sulphur. Since sulphur in a physically dissolved state is many times more efilcient in a cutting lubricant than when it is in the combined state, this is suflicient to give an excellent and superior cutting lubricant.

Other solvents among the naphthalene derivatives which are satisfactory, but notas eflicient as the above two, are as follows in the descending order of their suitability for use in this invention: heptaand higher chlorine derivatives of naphthalene;'mono-, di-, tri-, and tetra-chloro derivatives; decahydronaphthalene (decalin) halogen or chlorine bearing alkylated naphthalenes (methyl, ethyl, amyl, decyl, octadecyl etc.) coal tar oil out boiling between 400 F. and 600 F. and higher (largely a mixture of alkyl derivatives of naphthalene) and its halogen bearing derivatives; tetralin and other hydrogenated naphthalenes and their halogen bearing derivatives. Di-alkylbenzenes and similar high boiling alkylated benzenes (one or more alkyl groups) and their halogen bearing derivatives are suitable for this invention but are not as eilicient as the naphthalene derivatives. In fact the halogen bearing and chlorine bearing aromatic and alkylated aromatic compounds as a class are usable in my invention. 7

In preparing a cutting lubricant according to my invention, the following procedure is recommended. The petroleum lubricant is first mixed with the sulphur solvent in the proportion that it is calculated necessary for the amount of sulphur to be held in solution. The mixture is heated to slightly above the melting point of sulphur (or about 250 F.) and the sulphur is then stired in until all diss'olves. No chemical reaction takes place between sulphur and lubricating oil or halogen bearing aromatic derivatives at this temperature and the solution is purely physical. Only a few minutes are required for the solution to take place. Some specific examples of difierent mixtures of this new type of cutting lubricant with tests to show their value are given, by way of illustration only, and not by way of limitation. The sulphur may also be first dissolved in the sulphur solvent and then (in solution) added to the lubricating oil.

Example No. 1.-A mixture of 80 parts by weight of light lubricating oil and 20 parts by weight of mono-chloronaphthalene was heated to 250 F. and one part of sulphur was stirred in until it dissolved. A sample of this mixture stored at F. for several days did not precipitate sulphur. Tested in a 2" thread cutting machine it gas excellent results. The threads were extremely smooth. Its color was very light and its transparency was an aid to the operator in obtaining the best results, thus avoiding a draw-- back of the dark sulphuretted 'cutting oil containing chemically combined sulphur. 0n very cold mornings no trouble was encountered from difiicul'ty to fiow. A comparison was made between the results obtained with this lubricant and a highly recommended cutting oil containing chemically combined sulphur, which lubricant had a larger amount of sulphur than the lubricant of my invention. The test pipe threaded was a piece of very hard, used, oil well casing. A

number of threads .cut with the sulphur-combined lubricant. werecompared with a number of threads out with the new type lubricant. The latter threads were appreciably smoother and showed less tearing than the former, thus demonstrating the improved efliciency of-a physica solution of sulphur as a cutting lubricant. v

Example No. 2.A' mixture of 80 parts by weight of a light petroleum lubricant and 20 parts by weight of coal tar oil (B. P. range 400 F. to 580 F.) was heated to 250 F. and one part by weight of sulphur stirred in until it entirely dissolved. This cutting lubricant was used in a 2" thread cutting machine for two months with consistently superior results with respect. to the threads obtained while using it.

Example No. 3.-A mixture of 85 parts by weight of petroleum lubricant and 15 parts by weight of decalin was heated to 250 F. and one part by weight of sulphur was dissolved in it. This cutting lubricant when tested. in a thread cutting machine gave very satisfactory results.

Example No. 4.--A mixture of parts by weight of p'enta-chloronaphthalene and 90 parts by weight of a petroleum oil was a viscosity of 150 seconds at 100 F. was heated to 250 F. and 1 part by weight of sulphur stirred in until dissolved. On testing this mixture for stability at 0. F. for several days, it did not .precipitate out sulphur. It was very lightand transparent, having a 2 color (A. S. T. M.) and was entirely free of any odor. The cold test was not raised by the addition of the sulphur and chloronaphthalene. When tested on a thread cutting machine it gave results which were superior to any obtained from any cutting lubricant ever tested on this machine. Considerably less sulphur in the blend than was used in the above examples is sufiicient to give a good cutting lubricant. Even as little as .2 per cent sulphur in the blends of my invention gives satisfactory results. Generally, the sulphur content of this'type of cutting lubricant should lie between .1 per cent and 2 per cent. More will not be necessary and less will not be entirely satisfactory. The quantity of sulphur to be used is determined by the use to which the cutting oil will be put.

The addition of l per cent or 2 per cent of oleic acid to this type of cutting lubricant seems to have a slightly beneficial efiect but is not necessary.

This new type of cutting lubricant may be blended with the old sulphur chemical compound type cutting lubricant to improve the latter.

The petroleum lubricants used in the preparation of these cutting oils may be of naphthenic, paraflinic or mixed base source. They may be either raw or refined and should be selected so that the finished lubricant will have a viscosity of 100 to 300 seconds at 100 F. (S. S. U.). Naturally, cutting lubricants with viscosities outside this range may be useful but as a. rule are not as satisfactory as those within this range.

Although a cutting lubricant is the primary object of this invention, it is possible to obtain a high class extreme pressure gear lubricant by merely substituting a more viscous hydrocarbon lubricant for the relatively low viscosity oil used in preparing cutting lubricants in the foregoing compositions.

Having thus described my invention, I claim:

1. A composition of matter comprising in combination a major proportion of a lubricant and a minor proportion of a physical solution of elemental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising a I 2,283,486 halogen bearing alblated aromatic compound which is a sulphur solvent and'is itself soluble in said lubricant.

2. A composition oi matter comprising in combination a major proportion of a lubricant and a minor proportion of a physical solution of elemental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising a halogen bearing alkylated aromatic compound which is a sulphur solvent and is itself soluble in said lubricant.

3. A composition of matter comprising in combination a major proportion of a lubricantand a. minor proportion of a physical solution of elemental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising a halogen bearing alkylated naphthalene which is a sulhpur solvent and is itself soluble in said lubricant. v v

' 4. A composition of matter comprising in combination a major proportion of a lubricant and a minor proportion of a physical solution of elemental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising a chlorine bearing alkylated derivative of naphthalene which is a sulphur solvent and is itself. soluble in saidlubricant. I WALDQ L. STEINER. 

